Patient-ventilator synchrony is critical in achieving optimal oxygenation and ventilation. However,ventilator synchrony is difficult to quantify. Nurses often asses patient-ventilator dysnchrony (PVD) using a non- empirical approach, and clinical manifestations of dysychrony are not standardized. Identifying valid biobehavioral measures of this phenomenon will assist clinicians to reduce the complications of mechanical ventilation. Thus, the specific aims of this fellowship are to: 1) Identify biobehavioral markers (physiologic stability, agitation and patient behavior) of patient-ventilator dysnchrony and 2) Examine the effect of patient ventilator dysynchrony on the use of sedation. Patient ventilator dysynchrony will be identified using changes in airway pressure waveforms that will be obtained continuously over a 24-hour period. The bio- behavioral markers of patient-ventilator dysynchrony to be evaluated in this study will include physiologic instability (heart rate, SaO2, respiratory rate), agitation (actigraphy) and direct observation of patient behav- iors as well as amount of sedation use. Describing PVD will assist clinicians in early and accurate detection of dysynchrony, which may lead to reduction in risks associated with mechanical ventilation and sedation.